Screw type jack for vehicles



Jan. 2, 1951 v c. B. WOODWORTH SCREW TYPE JACK FOR VEHICLES Filed Sept. 4, 1946 Patented Jan. 2, 1951 UNITED z I p 1' 2,536,972; r seaEWTYPE JACK FOR VEHICLES GharleeB; Wdodworth, Port; DickinsomNr. Application September 4, 1946, serfalfloiiiiifliifl (01.. est-=98 7:"Claim's.

- "'i hepreseht inventibn relatesgenerally te v ehie'l'eli'fiting jacks.

More particularly" the invention is directed to certain-new and useful improvements in the lil ting-nut'sbf screw type I "l ne-principal obj ecto'i the inventionis' to-pr'ovide a screw typelifitingjack c 'racter'ized by rel ative fireedom i rom binding on: the application o'f efllb'ad thereto Anotherobjector the: invention is to provide a- Vehicle lifting Jacki-capable o'fi "being; relatively inexpensively produced anda characterized by the i ncrea'sedzutilization oil-metal. stampingstogether with the absence of: machining. operatiomsi Aa iurther objectl of the inventions-is to provide a; vehicle lifting. jack the various components of which may be expeditiously assembled in accue rate: relationships An additional objectoi. the; inventionis to pro?- eide'; a'n'improved nut-of novel: threaded, constructiomof general application;

Other; and further objects and advantages of theinyention-together withla clearerunderstandr ing; of the precise: nature thereof will: become more readily apparent to oneiskilled theart from a. consideration ofthe following, detailed specification takenrinconjunction with the accompanying. drawings inwhich: like reference numerals; refer to-like parts! throughoutv the severa! views andwherein:

Fig. 1 is an over-all perspective of a completely assembled jack. in accordance withthe present invention;

Fig. 2 is a fragmentary perspectiveview to an enlarged scale of the lifting nutshowniin Figs! 1 in assembled condition;

I Fig; 3 is a detailed perspective view of one of the toothed laminar plates forming. a-portionof the. lifting. nutof Fig. 2H and constituting an importantv feature of the present ir-w'ention;v and Fig. a is a. transverse cross-sectional view throughthe assembledlifting. nut. taken substan.- tially along. the. line 4-4. 'of..Fig.. 2..

' The present inventionconstitutes, an improvement over the lifting jack structure as particularly d'isclosedlinmy earlierv United: States Patent No. 2,060,780, i'ssued November. 1'0,.:11936.'.

} Referring now specifically and in detail .to the drawingsand particular-151' to Fig. 1- thereof, the

l ifting jackin accordance. with-the presentinvention is seen to comprise generally abase l-fl hava-nupwardly open,v vertically disposed socket H in which is rotatably mounted the. bottom end oi an: elongated cylindricalcshaft t2: termed:- with a helical-'- buttress thread: I3 and having; a load 2 engaging member in the form of" "a lifting: M inthreaded engagement therewith: An "(i-per ating handle 1 6" is-bi-furc'ated atone end FF and pifvotally attached; asbyme'ansofa suit pin 1 8; tb the to-pend'of't eshaft' 'l 2 for rotating-the latter; The base I is 'generallypyramidafi form and' isprovided-with a2 relativefiy flat bottom surface adapt'e tocon-tactthe-ground or other supporting. structure;

' ting nut" i4 is provided with upwardlyo'pem horizontally aligned notches 5' at on e" sidethereof adapted to engage velifclebuihger or otherconvenient:structure; 1t wil l be= *derstood tl ia't as the'operating'handle ismoved o eiiect rotation of the shaft I2, the liftingn is held' against rotation by the engagement of the notches I 5 with. the load, win -be caused ta move along: the shaft 2 a. manner that-will be apparent. For a runner und'ersta constructional details o'f the base l ll and operating --handle I 6; reference may be had 'to my" earlier Patent- Not. 2060;730; referred-to"previously-w Referring? now particularly to Fig.2; the i i-tingf nut I4 is seen to comprise a. generally shaped housing preferably formed: as" ash *e't' metal. stamping? 'amd'hav-ingi a curved: adapted to be wrapped around one-side t "shaft. L2. in. sliding engagement with the latter,

of the1ami-nar plat.es-2-2 Z2- areslightly'staggered on a: circular arcto provide a generally: concave surface having approximately the same. radius of curvature as that ofthe threaded: shaft t2. It will" be understood that. when assembledthe various adjacent buttress teeth. 24.- are in: alignmentza'longanincline corresponding. to the-helix angle of the threads 13 on the shaft- 12: with: which they are inmesh. The'assembly of laminar plates 22 thus constitutes: aninternally threaded :sector in threaded engagement with; the: exten- -nall.y threaded shafit- I2 diametrically opposite-to the blankesector formed. by the curved. portion of. theshousi'ng: M: whichis in slitline'engagernent dithe- Although the particular staggered arrangement of the laminar plates 22 as illustrated in Fig. 4 may, of course, be achieved in various ways, it is preferred to assemble the plates in position between the arms 20 with the teeth 24 in engagement with the thread l3 prior to drilling the apertures 23 therein. In this way the plates 22 may be held in a clamp during this drillin operation in the same position which they will occupy after final assembly, and the drilling of all the apertures as well as the insertion of the rivets 26 may be accomplished before the clamp is removed to insure proper alignment of the parts.

In the preferred embodiment illustrated in the drawings I have disclosed a buttress type thread, as the latter is particularly well-adapted for use in those applications where the force is to be transmitted substantially axially of the threaded shaft, to avoid any tendency to burst the nut, Such a thread is also readily adapted to be produced by relatively rough machining operations and it'is a feature of the invention that such an inexpensive rough thread may be employed on the shaft l2 due to the inherent tendency of the assembly of laminar plates 22, 22 constituting the lifting nut-to adjust themselves to accommodate slight irregularities in the thread. This construction, for the same reason, also provides an improved fitbetween each individual threaded shaft and lifting bolt. A further economy in manufacture will be noted in that as indicated above, the nut is preferably assembled in position on the shaft instead of being threaded thereon after machining.

In the ordinary use of vehicle jacks of the general type-described herein, the full load of the vehicle or other object to be lifted is ordinarily concentrated on the lifting hook or other load engaging device'lying entirely on one side of the screw member. This concentration of the load at one side of the conventional full threaded nut inevitably tends to produce a certain amount of binding or jamming between the engaging threads at the opposite side of the nut. As will be evident from the preceding description of my improved lifting nut, his binding action is virtually eliminated by the provision of a blank sector over the non-lifting portion of the nut, and it will "also be noted that this blank sector extends over considerable area to reduce the sliding frictional forces imposed upon each individual thread 13.

It is an additional important advantage of the present invention that the improved lifting nut is substantially self-lubricating over an extended period of usage. This result is brought about chiefly by the laminar assembly of the flat, toothed plates 22, 22, which may be individually soaked or-otherwise coated with a suitable lubricant prior to or during assembly. After having been assembled in face-to-face relationship, a considerable portion 'of such lubricant is retained between the inner faces of the various plates and bleeds or leaks out slowly to the teeth 24, as

required to replace the lubricant consumed by frictional engagement of the latter with the thread l3.

From the foregoing, it Will be apparent that there has been provided a markedly improved vehicle lifting jack embodying not only improved operating characteristics, but also being capable of inexpensive and expeditious manufacture as well as freedom from maintenance attention during its useful life. and in a highly competitive field such as that to which the present invention relates, such advantages constitute significant improvements.

Obviously numerous other modifications, alterations, and deviations from the specific structure disclosed herein, as a, preferred embodiment solely for purposes of illustration, will occur to one skilled in the art without departing from the spirit or scope of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A nut comprising a housing and a plurality of laminar plates mounted in Superimposed relation therein each plate having spaced teeth alon one edge and said plates being arranged to form an internally threaded sector for threaded engagement with a screw threaded shaft.

2. A'nut comprising a housing, a pluralit of superimposed laminar plates each having a substantially straight edge provided with spaced teeth thereon, and means mounting said plates face-to-face in said housing with their toothed edges defining a concave circular arc and with said teeth arranged in inclined alignment, to form an internally threaded sector for engagement with a screw threaded shaft.

3. In combination with a jack having a rotatable, screw-threaded shaft, a lifting member comprising a housing having a portion adapted to slidably engage one side of said shaft'and spaced arms extending laterally from the opposite side thereof, a plurality of superimposed laminar plates each having spaced teeth along one edge thereof adapted to engage said shaft, and means mounting said plates face-to-fac between said arms.

4. A jack comprising, a base, an elongated shaft having its lower end rotatably mounted in said base and including a screw thread extending helically along substantially its full length, means for rotating said shaft, and a lifting nut comprising a housing having a curved portion wrapped around one side of said shaft in sliding engagement with the latter, horizontally spaced arms extending laterally from the opposite side thereof, a plurality of superimposed laminar plates each having spaced teeth along one edge thereof, and means mounting said plates between said arms with said teeth in engagement with said thread.

5. A lifting jack comprising, a base having a socket therein, an elongated shaft having its lower end rotatably mounted in said socket and including a screw thread extending helically along substantially its full length, an operating handle pivotally connected to said shaft adjacent its top end for rotating the latter, and a lifting nut comprising a housing having a curved portion wrapped around one side of said shaft in sliding engagement with the latter, horizontally spaced arms extending laterally from the opposite side thereof, a plurality of fiat superimposed laminar plates each having spaced teeth along one edge thereof, and means mountin said plates between said arms with said teeth in engagement with said thread.

6. A vehicle lifting jack comprising, a. base having its bottom surface adapted to contact the ground and including an upwardly open socket vertically disposed therein, an elongated cylindrical shaft having its lower end rotatably mounted in said socket and including a buttress thread extending helically along a substantial portion of its length, an operating handle piv-a otally connected to said shaft adjacent its top end for rotating the latter, and a lifting nut comprising a generally U-shaped housing having a curved portion wrapped around one side of said shaft in sliding engagement with the latter, horizontally spaced arms extending laterally from the opposite side thereof, a plurality of flat laminar plates each having spaced buttress teeth along one edge thereof, and means mounting said plates between said arms with said teeth in engagement with said thread.

7. A vehicle lifting jack comprising, a base having its bottom surface adapted to contact the ground and including an upwardly open socket vertically disposed therein, an elongated cylindrical shaft having its lower end rotatably mounted in said socket and including a buttress thread extending helically along approximately its full length, an operating handle pivotally connected to said shaft adjacent its top end for rotating the latter, and a lifting nut comprising a generally U-shaped housing having a curved REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,132,763 Claymier Mar. 23, 1915 29 2,060,780 Woodworth Nov. 10, 1936 2,294,056 Thompson Aug. 25, 1942 2,386,824 Tinnerman Oct. 16, 1945 

